This paper describes the preparation and characterization of unimorph actuators for adaptive optics based on the Pb(Zr0.52Ti0.48)O₃(PZT52) thin film.The actuator utilizes a unimorph membrane (diaphragm) structu re consisting of an active PZT piezoelectric layer and a passive ZrO₂/Si composite layer.The PZT layer in the unimorph actuator is dri ven by ring-shaped interdigitated electrodes (IDT-mode). To fabricate the diaphragm structures,the Si (100) wafer is used as substrate,o n which PZT52and ZrO_2layer are deposited by a modified sol-gel process.The PZT layer can be crystallized with preferred (110) orientation by using PbTiO₃(PT) material as a seed layer.The Al reflective layer is deposited and patterned into top electrode geo met ries by lithographic process,subsequently.The electrode spacing is 50μm and the diameter of the inactive circular regions is 2mm.The diaphragms are released using orientation-dependent wet etching (ODE) with 5－10μm residual silicon layers.The size of the diaphragms is 12mm in diameter and the outer IDT diameter (10.5mm) is fixed at 87.5% of the diaphragm diameter.The measured maximum cent ral deflection at 100kV/cm is approximately 6.5μm.The deflection profiles are also modeled using finite elemen t method (FEM) and their intrinsic strain behaviors are evaluated.